Most lionesses will have reproduced by the time they are
four years of age. Lions do not mate at any specific time
of year, and the females are polyestrous. As with other
cats, the male lion's penis has spines which point
backwards. Upon withdrawal of the penis, the spines rake
the walls of the female's vagina, which may cause
ovulation. A lioness may mate with more than one male when
she is in heat; during a mating bout, which could last
several days, the couple copulates twenty to forty times a
day and are likely to forgo eating. Lions reproduce very
well in captivity.

During a mating bout, a couple
may copulate twenty to forty times a day for several days; the
ruff of the female is clearly visible. The average gestation
period is around 110 days, the female giving birth to a litter
of one to four cubs in a secluded den (which may be a thicket,
a reed-bed, a cave or some other sheltered area) usually away
from the rest of the pride. She will often hunt by herself
whilst the cubs are still helpless, so as to stay close to the
thicket or den where the cubs are kept. Usually, the mother
does not integrate herself and her cubs back into the pride
until the cubs are six to eight weeks old. However, sometimes
this introduction to pride life occurs earlier, particularly
if other lionesses have given birth at about the same time.

For instance, lionesses in a
pride often synchronize their reproductive cycles so that they
cooperate in the raising and suckling of the young (once the
cubs are past the initial stage of isolation with their
mother), who suckle indiscriminately from any or all of the
nursing females in the pride. In addition to greater
protection, the synchronization of births also has an
advantage in that the cubs end up being roughly the same size,
and thus have an equal chance of survival. If one lioness
gives birth to a litter of cubs a couple of months after
another lioness, for instance, then the younger cubs, being
much smaller than their older brethren, are usually dominated
by larger cubs at mealtimes consequently, death by starvation
is more common amongst the younger cubs.